Synthesis of oxidovanadium complexes containing coumarin and naphthalene: bromoperoxidase activity and DNA/BSA binding

Abstract

Two tridentate Schiff base ligands, L1 and L2 , have been introduced in the synthesis of mononuclear oxidovanadium complexes with a co-ligand 1,10-phenanthroline. Two mononuclear complexes, [VO(L1)(1,10-phen)] (1) and [VO(L2)(1,10-phen)] (2), have been synthesized in high yields by reactions with [VO(acac)2] in 1:1 ratio in methanol under reflux with 1,10-phenanthroline as co-ligand. X-ray crystallographic studies unveil the structures of 1 and 2 showing L1 and L2 bind in O^N^O coordination. The complexes were characterized by using UV-Vis, IR, NMR and Mass spectral techniques. The physiochemical properties have been interpreted by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The mimicking of vanadium haloperoxidase was investigated by bromination of phenol red in the presence of bromide and H2O2 with a rate of 2.68 × 102 (mol/L)−2 s−1. The DNA and BSA protein binding interactions of 1 and 2 have been explored by UV–Vis and fluorescence spectral methods; viscosity measurements reveal that the complexes interact with CT-DNA through intercalation in the order [VO(L1)(1,10-phen)](2.71 × 104) > [VO(L2)(1,10-phen)](9.67 ×103). The complexes exhibit binding interactions with BSA protein.